Heat exchange



March 28, 1944. E, BERTRAM ET AL 2,345,319

HEAT EXCHANGE Filed March 30, 1942 Patented Mar. 28, 1944 'l UNITEDSTATES PATENT ori-ice name' YA. Be ana pavia Fulton, Flushing, N. Y.,assignors to The Lum--A mus Company, New York, N. Y., a. corporation ofDelaware application March so, 1942, serial No. 438388 y s claims. (ci.esi-11) This invention relates to a fractionation column, bubble tower,vapor absorption device or-other type of liquid and gas contactapparatus, and more particularly t an apparatus of this generalcharacter wherein hot or cold mediums may be introduced at one or morepoints into the column ioraccurately controlling the temperaturetherein. I Y

An object of the invention is` toY provide a fractionation column, suchas an ammonia-absorponunit with an improved form of heat exchanger forthe more accurate temperature control therein.

A further object of the invention is to c'on-A struct a liquid contactcolumn in such a manner that the plurality of heat exchangers'used maybe readily inserted into thecolumn or removed therefrom.

A still further object of the invention is to provide an improved formof 4absorber in which each ofthe heat exchange units is provided with aiixed top tray having a plurality of perforations therein'above the tubebundle for the purposeof collecting descending liquids Vand dis,-

,` tributing' them over the .tubes of the bundle in heat exchangerelation.

l While theinvention may be used in various types-of fractionation orabsorption columns, we-

have shown it in the accompanying drawing as applied to a multiple-deckbubble tower. v

In the drawing:

Fig-1 is a side view of the fractionation tower drawn partly inGross-section and showing the bubble decks and the V.relation therewithof the heat exchangers. i

gig. 2 is'a vertical 'section through one of the heat exchangers takenon line 2-2 of Fig. 1

looking in the direction of the arrows.

Fig'. 3 is 'a side elevational view of.one of the heat-exchangers withportions thereof broken away to inustrate the tray support.

Fig. 4 Visa top4 plan view of one of the heat fractionation tower Il) ofsuitable diameter and height is provided with a suitable number ofhorizontal bubble decks I3. The column is pro- 'vided with the customaryinlet and outlet conduits for introducing and discharging vapors andliquids at the top and bottom thereof as willV be hereinafter referredto.

l0 of the tower.

` preferably below each pair-or bubble decks is,

' is a horizontal section l5 for supporting a complete.heat exchangeunit I7. YThese sections may be of any suitable construction to rigidly5 supportthe exchanger units. In the present insaid frames and to befreelysupported by thev other frame as a. bottom guide. The free end hasa iioating head cover and'thus Nis free to l5 move with temperaturevariations.

Referring to Figs. 2, 3 and 4, each heat exchanger unit ll preferablycomprises a plurality of horizontal tubes 23 secured to conventionaliioating tube sheet v251m the free end, and a` 2() fixed, tube sheet 2lon the other. The iixed tube sheet 2l is provided with a manifold orYchannel 29 having inlet and outlet feed conduits 3U Y through which hotor cold iiuid is circulated through the tube lbundle and the free endhas a channel 25a.

Bailies 2i and .2in extend between the sides of the column and the heatexchanger guide angles 22. As will be seen in Fig. 2, the upper baille21a tends to prevent passage of vapors through Y 30 the column exceptthrough the heat exchange unit, whereas the companion baiiie 2l at thelower part of the heatY exchange unit serves aV complementary purpose.These bames prefer- Y ably have a perforation to make them freedraining.The liquid Awhich accumulates on the respective decks is carrieddownward through the customary downppes 24 into the'usual liquid' traps24a so that therecan be no bypassing of the upwardly moving vapors.

Each heat exchange unit is providedV4 va` liquid distributing tray 3l,having .upstanding side walls 33, such tray being secured to the-xedtube sheet 2l and extending across the top of the tubes in slightlyspaced relation thereto to a point adjacent the opposite oatingtubesheet `25, from which it is supportedby dowels 26.

' The liquid from downpipe 2I,Ywhieh overiiows the trap chamber 24a, andoverruns the tray 3l, is thus distributed by the perforations, over-Athe tubes 23.

Each'heat exchange unit is also provided with a liquid collecting trayor plate 35 welded to the fixed tube sheet 21 below theY tube bundle;such tray being imperiorate. This bottom plate 35 Throughout the columnand in this instance, has upstanding side walls 3l but is open at theEach heat exchange unit Il is.' arranged to be demountably secured toone of 2 enen adiacentthe noaung tube sheet 2s from' /which it is spaceda sumcient distance to permit 'the'iree passage of downcoming liquid.Vertical straps or braces I9 are secured to the top tray 3i land thelower tray 35 for supporting the4 freejend of the lower tray,

We have found that a column which is provided with one or more of theremovable heat exchanger units a's heretofore described, can beyaccurately controlled as to temperature Vby tributes over the tubes ofthe bundle where it is '2d collected on bottom plate 35 and drips fromthe open free end 38. The Yliquid flowing from the bottom plate 95passes" down in a thin film to.

. the bubble deck immediately below the 4particuper pound.

- seriously obstructed.

lar heat exchanger unit.

We have found particular equipment as an ammonia absorber, in which airand ammonia' are introduced at the point l2 and the water is introducedat 44. The air and unsuccess in using this rich aqua is removed at 48. Adrain 49 is provided for cleaning out the column from time to.

time. 4 'As is well known, the production of a predeterminedconcentration of aqua' is ai'unction of the temperature at theabsorption stage. Not only is it necessary to have a minimum temperatureto avoid boiling oi! the ammonia, but it is necessary to have a somewhatlower temperature in order to assure the absorption with the minimumamount 'of watercirculation. Furthermore, in ammonia' absorption, theaveragelatent heat at 90 F., for example, is approximately 488.5 B. t.u.

In accordancl with our invention, we have foundv it possible 'to'circulate cooling. water througheach .of the Vheat exchange units inseriesj beginning with the coldest water at the bottom, and we were ableto obtain a high concentration of aqua with the minimum ilow of waterwithout requiring external pumps, heat exchangers, etc. The arrangementfor supporting and securing the heat exchange units through the lateralextensions of the tower formed by the frames I9 and f 19a has alsoproved especially satisfactory on this type of unit for it is onlynecessary to have a relatively small diameter column and yet the heatremoved is/ jso great that comparatively large bundles are requiredwiththe usual temperature 1 0i' available coolingwater. Such bundlescan beprojected through. the column with portions 'of shown without departingfrom the invention.

Such modifications are thus consideredwithin the diameter andtransversely centered inthe tower to provide a pair of vertical vaporpassages at opposite sides of thebundle, a foraminous liquiddistributingtray overlying said tubebundle and arranged to receive downowing liquidand shed a rain of the liquid upon said tubing, a collecting trayunderlying the tube bundle to receive said liquid-after it has' passedthrough the bundle, a baille within the tower` and disposed atapproximately: the lower level of the tube bundle and closing' theAlower end 'of one of said passages, and'a baffle within the tower anddis- L posed at approximately the upper-level of the tube bundle andclosing the upper end of the other of said vapor passages, said traysand baiiles being constructed and :arranged to cause vapor ascendingwithin the' towerfrom beneath the tube bundle to flow through theiattercrosswise of said 'I rain of liquid. r

2. In a tower for the countercurrent contact of a downilowing liquid anda rising vapor-f said tower having. diametricaliy located lateralVextensions, one of said extensions being closed at its outer end, aremovable heat exchanger unit comprising a bundle of horizontal tubingexposed within the tower, means to circulate temperatureconditioningiiuid through said tubing, said means including a head at one end .ofsaid bundle detachably secured to the other of. said extensions andclosing the outer end thereof, the bundle extending across the interiorof the tower and into kboth of said extensions for support thereby andbeingwof materially less yhorizontal width than the mternalidiameter ofthe tower to provide a pair of vertical vapor passages at oppositesidesof the bundle, a Ioraminous liquid-distributing tray overlying saidtubebundle and `arranged to receive downiiowing liquid and shed a rain'of the level of the tubebundle and closing the lower end of one of saidpassages; and a'baiiie iixed within the tower at approximately the upperlevel of the 'tube bundle and` closing the upper end of the other ofsaid passages, said trays and baiiles being constructed and arranged tocause vapor ascendingfwithin the tower from beneath the tube bundle fthetube bundles extending beyond the actualdiameter ofthe column due to thelarge spaces'provided by the nozzles. The dotted line I0 in Fig. 4

forexample, indicates the extent of the column 'although" the effectivecross section in the vicinity construction there is no objectionablerestriction in the vapor space so that .the vapor path is not It will beapparent that our invention is ,applicable to different forms offractionation or to ilow .throughthe latter crosswise of said rain ofliquid, said unit including the tube bundle and a downfiowing liquid andarising vap'or, said tower having` diametrically' located apertures,frames extending around said'apertures and said extensions being closedat its outer end, a removable heat exchanger unit comprising abun'dleofhprizontal tubing exposed within the tower, means to circulatetemperature-conditioning uid through said tubing, said means including ahead at one end of said bundle detachably asiasie secured to the otherof said extensions and closing the outer end thereof. the bundleextending across the interior of the tower and into-both of saidextensions for support thereby and being of' a materially lesshorizontal width than the internal diameter of the tower to provide apair oi' vertical vapor passages at oppositesides of the bundle, a.foraminous liquid-distributing tray overlying said tube bundle andarranged to receive downowing liquid and shed a rain of the otherfofsaid passages, said trays vand baiiles being constructed and arranged tocause vapor ascending within the tower `from beneath the tube bundle toflow through the latter crosswise.

of said rain of liquid; and` track means xed within the tower andextending between said extensions, said unit including the tube bundleand trays being removable endwise from the tower along said track meansafter release oi said bundle Ahead from the respective tower extension.

4. In a tower for contact of a downowing liquid and a vapor, a bundle ofheat exchanger `tubing exposed within the,tower and disposedhorizontally therein, means to circulate temperature-conditioning fluidthrough said tubing, a

through the bundle, said bundle being of mate-- rially less width thanthe internal diameter of the tower and being transversely centeredwithin thetower to afford spaces at opposite sides of the bundle, andvapor-directing means associated with said opposite'sides of the tubebundle, the said trays and the said vapor-directing means 'beingconstructed and arranged `'to constrain the vapor within the tower toiiow through the tube bundle crosswise oi' said rain of liquid.

5. In a tower for contact of a downilo'wing liquid and a vapor. a heatexchanger unit comprising a bundle of heat exchanger tubing exposedwithin the tower and` disposed horizontally therein, means to circulatetemperature-conditioning uid through said tubing, a foraminousliquid-distributing tray overlying said tube bundle and arranged toreceive downfiowing liquid and shed a rain of the liquid upon saidtubing, and a collecting tray underlying the tube bundle to receive saidliquid after it has passed through the bundle, said bundle being ofmaterially less width than the internal diameter of the tower and beingtransversely centered within the tower to afford spaces at oppositelsides of the bundle; means supporting said'unit within the tower forhorizontal endwise removal therefrom; and

vapor-directing means associated with said opposite sides of the tubebundle, the said traysand the said vapor-directing means beingconstructed and arranged to constrainl the vapor within` the tower toiiow through the tube bundle crosswise of said rain of liquid.

6. A heat exchanger unit for installation in a vapor-liquid contacttower crosswise of the latter and for removal transversely of the tower,comf prising a bundle of 'parallel horizontal tubes, a iixed tube sheetsecured to one end of/'said tubes; aiioating tube sheet -secured to theopposite end of said tubes, means for circulating a heat exchange mediumthrough the tubes, a foraminous liquid-distributing tray overlying thetube bundle to shed a rain of liquid upon the tubes, an imperforateliquid-collecting tray underlying the tube bundle, both of said traysbeing secured at one end thereof to one of the tube sheets, a

slidable supporting connection between the other tube sheet and theopposite end portion of said foraminous tray to support the latter andpermit movement of the floating tube sheet under expansion andcontraction of the tubes, and a` suspen-

